In the previous issue of Critical Care, Caille and colleagues [1] evaluated the ability of transthoracic echocardio-graphy TTE to predict cardiac-related weaning failure and to assess th
Trang 1In the previous issue of Critical Care, Caille and colleagues
[1] evaluated the ability of transthoracic
echocardio-graphy (TTE) to predict cardiac-related weaning failure
and to assess the hemo dynamic changes before and 30
minutes after the start of a spontaneous breathing trial
(SBT) Th e authors measured maximal velocities of
mitral E and A waves, deceleration time of E wave (DTE),
maximal velocity of E’ wave measured by tissue Doppler
at lateral mitral annulus, and left ventricular (LV) stroke
volume
Weaning failed in 23 of 117 patients, and failure was of
cardiac origin in the majority (20 of 23) of them In
patients with weaning failure, a signifi cantly lower heart
rate and E/E’ ratio and a higher left ventricular ejection fraction (LVEF) were observed before SBT During SBT, signifi cant increases in cardiac output, systolic arterial pressure, and E/A relation and a nonsignifi cant increase
in E/E’ were observed, with signifi cant shortening of DTE Weaning failure was observed in 17% of patients with LVEF of greater than 50%, 13% of patients with LVEF
of 35% to 50%, and 31% of patients with LVEF of less than 35% Before SBT, DTE was signifi cantly shorter and E/E’ was signifi cantly higher in patients with LVEF of less than 35% During SBT, E/A increased and DTE decreased signifi cantly in patients with LVEF of less than 50%
If these results are translated into simple clinical language, patients with weaning failure were tachycardic and had depressed systolic function and diastolic dys-function (short DTE) with elevated LV fi lling pressure (high E/E’ ratio) before SBT During SBT, a further increase
in LV fi lling pressure (increased E/A and E/E’ ratio) and deterioration of diastolic function were observed
TTE was therefore able to identify patients who were at risk of cardiac-related weaning failure by measuring relatively simple and reproducible variables (LVEF, E/E’, and DTE) before SBT Moreover, hemodynamic changes (increase of pulmonary artery occlusion pressure [PAOP] and changes in stroke volume) during SBT can be followed by repeated TTE
Unsuccessful weaning from mechanical ventilation occurs in approximately 20% to 30% of patients and is related to prolonged mechanical ventilation, length of stay in the intensive care unit, and increased morbidity and mortality [2] It is more frequent in patients with chronic obstructive lung disease or pre-existing heart disease or both Cardiac failure is usually due to cardio-genic pulmonary edema or to inadequate response to the increased oxygen demand [3,4] Hemodynamic monitor-ing by pulmonary artery catheter (PAC) is traditionally used in patients with unsuccessful weaning for monitor-ing PAOP, cardiac output, and mixed venous oxygen saturation and enables proper diagnosis and treatment
Abstract
Cardiac-related failure of weaning from mechanical
ventilation is an important reason for prolonged
mechanical ventilation, intensive care unit treatment,
and increased morbidity and mortality When
transthoracic echocardiography (TTE) is routinely
performed before a weaning trial, patients at high risk
of cardiac-related failure can be detected by low left
ventricular (LV) ejection fraction, diastolic dysfunction,
and elevated LV fi lling pressure During the weaning
trial, a further increase of LV fi lling pressure and
progression of diastolic failure can be observed by
repeated TTE Owing to certain limitations concerning
patients and methodology, TTE cannot be employed in
every patient and invasive hemodynamic monitoring
is still mandatory in selected patients with repetitive
weaning failure
© 2010 BioMed Central Ltd
Hemodynamic changes during weaning: can we assess and predict cardiac-related weaning failure
by transthoracic echocardiography?
Gorazd Voga*
See related research by Caille et al., http://ccforum.com/content/14/3/R120
C O M M E N TA R Y
*Correspondence: gorazd.voga@guest.arnes.si
Medical Intensive Care Unit, General Hospital Celje, Oblakova 5, 3000 Celje,
Slovenia
Voga Critical Care 2010, 14:174
http://ccforum.com/content/14/4/174
© 2010 BioMed Central Ltd
Trang 2with vasodilators, diuretics, and inodilators Since
invasive hemo dynamic monitoring is less frequently
used, noninvasive alternatives for assessment of
cardiac-related weaning failure such as measurement of baseline
brain natriuretic peptide values and its increase during
weaning, hemoconcentration during SBT, and
echo-cardio graphic examination before and during weaning
have been studied [5-7] Echocardiography allows the
assessment of systolic and diastolic cardiac function and
etiologic diagnosis of cardiac disease Th rough the
analysis of transmitral fl ow and tissue Doppler velocities,
it is also possible to estimate the LV fi lling pressure
change during weaning [8]
Concerning the results of the study, two clinically
important questions should be answered First, should
we routinely use TTE in patients before weaning? If we
take into account the ability of TTE to predict diffi cult
weaning, the answer is undoubtedly yes Th e problem is
the fact that an experienced echocardiographist is
required for performing and interpreting the TTE in such
patients [9] Moreover, TTE cannot be performed in all
patients, and patients with inadequate visibility and
image acquisition, atrial fi brillation, and paced rhythm
must be excluded [1] Despite these drawbacks,
echo-cardiography is increasingly used in the majority of
intensive care units as the most common available
non-invasive method for objective hemodynamic assessment
Th erefore, it should be routinely used before SBT for
hemodynamic assessment and estimation of the risk of
cardiac-related weaning problems
Th e second question is whether we can detect and
monitor the hemodynamic changes during SBT
accu-rately enough to titrate the treatment of cardiac failure
Th e answer is probably no It is technically impossible
and absolutely too time-consuming to perform TTE
every few minutes during SBT Besides, the changes of
specifi c variables measured by TTE are relatively small
and cannot be used for treatment adjustment
In real life, the practical approach should include TTE
before SBT and treatment in patients who are at high risk
of weaning failure In the case of cardiac-related weaning
failure, the second SBT should probably be performed with close hemodynamic monitoring by PAC
Abbreviations
DTE, deceleration time of E wave; LV, left ventricular; LVEF, left ventricular ejection fraction; PAC, pulmonary artery catheter; PAOP, pulmonary artery occlusion pressure; SBT, spontaneous breathing trial; TTE, transthoracic echocardiography.
Competing interests
The author declares that he has no competing interests.
Published: 7 July 2010
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doi:10.1186/cc9085
Cite this article as: Voga G: Hemodynamic changes during weaning: can
we assess and predict cardiac-related weaning failure by transthoracic
echocardiography? Critical Care 2010, 14:174.
Voga Critical Care 2010, 14:174
http://ccforum.com/content/14/4/174
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